Respiratory mask



FIG. 1 is a front perspective view showing a respiratory mask according to our new ornamental design;

FIG. 2 is a reverse perspective view thereof;

FIG. 3 is a front view thereof;

FIG. 4 is a rear view thereof;

FIG. 5 is a top view thereof;

FIG. 6 is a bottom view thereof;

FIG. 7 is a left side view thereof; and,

FIG. 8 is a right side view thereof.

The broken lines, shown throughout the views, represent the portions of the respiratory mask, which form no part of the claimed design. 

CLAIM The ornamental design for a respiratory mask, as shown and described. 